code:

---

$search_for_line="our text we are looking for"
$file="c:\temp\our_file.txt"
;
IF (Open(1,$file,1) = 0)
   $line=ReadLine(1)
   $found="no"
   WHILE (@error = 0)
      IF (Instr($line,$search_for_line) <> 0)
         $found="yes"
      ENDIF
      $line=ReadLine(1)
   LOOP
   IF Close(1)
   ENDIF
   ;
   ; - append to file -
   ;
   IF (found <> "yes")
      IF (Open(1,$file,5) = 0)
         IF (WriteLine(1,$search_for_line+@crlf) <> 0)
            ? "Warning KIX-WriteLine: error @error (@serror)."
         ENDIF
         IF Close(1)
         ENDIF
      ENDIF
   ENDIF
ENDIF

---